Ray Gardener wrote:
> I was wondering if anyone had or is planning
> to collect MacPOV benchmarks on the new PowerMac G5.
> Apparently the floating-point performance is exceptional.

Yeah.  Although if you read the fine print in the veritest pdf, it becomes
clear that they rather lied about some of that.  Used lousy compilers for
the competition, disabled their hyperthreading, etc.  Used a fast but
memory-inefficient malloc library for their own tests.  Used compiler flags
that aren't useful in realworld apps.  If you compare to, say, Dell's
benchmarks of their own systems (which are probably similarly deceptive),
Apple's are competitive but not the best.

Also remember that POV is single threaded, so you won't benefit from
multiple processors.  It is very difficult to multithread an application
like POV, so it's unlikely to happen soon.  There existed a multithreaded
version out there somewhere, but AFAIK it's not up-to-date (Thorsten would
know).

Enough of the bad news... It's possible that the Altivec SIMD unit does make
the G5 the fastest desktop for some applications (Photoshop, codebreaking,
FFT).  IIRC the G4-optimized version of POV uses Altivec, which would help
in the G5 code too.  And render speeds would benefit immensely from the
increased memory bandwidth in the G5.

Thorsten Froehlich wrote:
>The systems ship in August, and that doesn't mean the compilers used to
>benchmark it are available on Macs.  To be precise, to benchmark its Power
>processors (and the PowerPC 970 processor is just a stripped down Power4
>with a SIMD extension), IBM always uses IBM C for AIX, and
>IBM VisualAge C++ Professional for AIX, benchmarking on, well AIX as you can
>for example see on the SPEC results page:
><http://www.spec.org/cpu2000/results/res2002q4/cpu2000-20021111-01822.html>

It was compiled with GCC 3.something.

>And the only other currently available compiler support it, which is gcc, is
>unfortunately, substandard as far as optimisations for non-x86 targets, and
>Power(PC)) processors in particular, are concerned.  The only compiler
>generating code with reasonable performance for Mac OS is Metrowerks
>CodeWarrior, and it usually takes Metrowerks a few month before optimisation
>for a specific processor is supported.

Apple is releasing a G5-optimizing version of GCC as part of the free
devtools upgrade (XCode I think it's called).  I don't know how good their
optimizations are, but they are there.

So, it may be possible to get them sooner.  Although as Thorsten mentioned
in the Mac thread, some POV developer would have to go buy a G5 in order to
optimize, which would be a tad expensive for a free software project and is
unlikely to happen immediately.

Mike

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